Sheet transport position and jam monitor

Abstract

A sheet transport system ( 20 ) comprising at least one sheet transporter ( 30,36 ) that receives and hands off a sheet being transported by the system so as to transport the sheet from a first position to a second position, wherein the at least one transporter ( 30,36 ) comprises at least one orifice ( 44 ) through which air is aspirated to create a vacuum that grips a sheet when it is received by the transporter ( 30,36 ); a vacuum system coupled to the at least one orifice ( 44 ) controllable to aspirate air through the at least one orifice ( 44 ) to grip the sheet; at least one vacuum sensor ( 60 ) that generates signals responsive to magnitude of vacuum of the at least one orifice ( 44 ); and a controller ( 49 ) that receives the signals generated by the at least one vacuum sensor ( 60 ) and provides a signal indicative of a location of the sheet in the transport system ( 20 ) from the signals.

1. A sheet transport system comprising:
 at least one sheet transporter that receives and hands off a sheet being transported by the system so as to transport the sheet from a fire position to a second position;  
 a plurality of sensors that generates signals responsive to a position of a sheet as it is transported by the transport system;  
 a display screen; and  
 a controller that receives the signals generated by the sensors and uses the signals to provide a real time visual display on the screen, of an image of a sheet, superimposed on an image of the transport system, as it moves through the transport system.  
 
   
   
     2. A sheet transport system according to  claim 1  wherein the visual display shows the sheet in continuous motion moving through the transport system. 
   
   
     3. A sheet transport system according to  claim 1  wherein visual display displays a plurality of such sheet images simultaneously as the sheets are transported by the transport system. 
   
   
     4. A sheet transport system according to  claim 3  wherein each of said sheets is identified on said display by a designation of said sheet. 
   
   
     5. A sheet transport system according to  claim 4  wherein the designation comprises identification numbers. 
   
   
     6. A sheet transport system according to  claim 4  wherein if a malfunction occurs in the transport system and at a particular location in the transport system a sheet is improperly transported, the particular location is indicated on the display screen. 
   
   
     7. A sheet transport system according to  claim 1  wherein the display screen is comprised in a video monitor. 
   
   
     8. A sheet transport system according to  claim 1  wherein the sheet at least one transporter comprises:
 at least one orifice through which air is aspirated to create a vacuum that grips a sheet when it is received by the transporter;  
 a vacuum system coupled to the at least one orifice controllable to aspirate air through the at least one orifice to grip the sheet;  
 at least one vacuum sensor that generates signals responsive to magnitude of vacuum at the at least one orifice; and  
 a controller that receives the signals generated by the at least one vacuum sensor and provides a signal indicative of a location of the sheet in the transport system from the signals.  
 
   
   
     9. A sheet transport system according to  claim 8  wherein the vacuum system is controllable to release air to the at least one orifice to release the sheet. 
   
   
     10. A sheet transport system according to  claim 8  wherein the controller uses signals from the at least one vacuum sensor to determine if a sheet being transported by a transporter of the at least one transporter is being transported properly. 
   
   
     11. A sheet sport system according to  claim 8  wherein an orifice of the at least one orifice is a suction cup. 
   
   
     12. A sheet transport system according to  claim 8  wherein the vacuum sensor is a pressure sensor. 
   
   
     13. A sheet tort system according to  claim 8  wherein the vacuum sensor is a flow meter. 
   
   
     14. A sheet transport system according to  claim 8  wherein the controller determines that a transporter of the at least one transporter is gripping a sheet being transported by the transport system and that the sheet is gripped properly if signals from a vacuum sensor of the at least one vacuum sensor indicate that vacuum sensed by the sensor is greater than a first pre-determined level of vacuum. 
   
   
     15. A sheet transport system according to  claim 8  wherein the controller determines that a transporter of the at least one transporter is not gripping a sheet being transported by the transport system if signals from the at least one vacuum sensor indicate that vacuum sensed by the at least one vacuum sensor is less than a second pre-determined level of vacuum. 
   
   
     16. A sheet transport system according to  claim 8  wherein the controller determines that a transporter of the at least one transporter is gripping a sheet being transported by the transport system, but that the sheet is gripped improperly, if signals from a vacuum sensor of the at least one vacuum sensor indicate that the vacuum sensed by the sensor is between the first and second vacuum levels. 
   
   
     17. A sheet transport system according to  claim 1  wherein the at least one transporter comprises a plurality of sheet transporters. 
   
   
     18. A sheet transport system according to  claim 17  wherein sheet transporters of the plurality of sheet transporters seriatim receive and hand off a sheet being transported by the system so as to transport the sheet from the first position to the second position. 
   
   
     19. A sheet transport system according to  claim 1  wherein a transporter of the at least one transporter is a rotary transporter, which rotates about an axis to receive and hand off a sheet being transported by the transport system. 
   
   
     20. A sheet transport system according to  claim 1  wherein the sheet transport system is a transport system that transports sheets printed in a printing system comprising at least one printing station and wherein the first and second positions are positions of the sheets in the printing system. 
   
   
     21. A sheet transport system according to  claim 20  wherein at least one of the first and second positions is a position in a printing station of the at least one printing station. 
   
   
     22. A sheet transport system according to  claim 21  wherein the printing station comprises an impression roller. 
   
   
     23. A sheet transport system according to  claim 22  wherein the first position in the printing station is a position at which a sheet is removed from the impression roller. 
   
   
     24. A sheet transport system according to  claim 22  wherein the second position in the printing station is a position at which a sheet is mounted on the impression roller.